Three stage manual knife sharpener



FIG. 1 is a front elevational view of a three stage manual knife sharpener showing our new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a right end elevational view thereof; and,

FIG. 6 is a left end elevational view thereof.

The broken lines in FIGS. 1-2 and 4-6 illustrate portions of the design that form no part of the claim. 

The ornamental design for a three stage manual knife sharpener, as shown and described. 